Effect of Molecular Structure on the Photophysical Properties, the Photoreactivity With Dna and the Photobiological Activity of Monofunctional Pyridopsoralens

Abstract— 7‐Methyl‐pyrido[4,3‐c]psoralen (2N‐MePyPs) has been synthesized in order to investigate the possible effect of the position of the pyridine‐nitrogen atom on the photoreactivity towards DNA and the photobiological activity of pyridopsoralens, a new family of psoralen derivatives. In comparison to its isomer, 7‐methyl‐pyrido[3,4‐c]psoralen (MePyPs), 2N‐MePyPs shows a 2.5 times lower DNA photobinding capacity. Photobiological experiments with diploid yeast (Saccharomyces cerevisiae) reveal that this compound differs strikingly from its isomer MePyPs. It has only a weak antiproliferative potential and, per unit dose, a lower capacity than MePyPs for the induction of nuclear genotoxic effects. With respect to these latter features, 2N‐MePyPs resembles the monofunctional furocoumarin 3‐CPs.